Power skin care brushes, such as those useful for cleansing of the facial region, are typically driven directly, such as by a drive shaft or shafts, gears and a motor. The skin brush typically includes a single brushhead, with a plurality of bristle/filament tufts, which move in unison. Some brushheads rotate (360°) in one direction continuously, while others oscillate through a selected angle. The higher frequency skin brushes are often referred to as sonic or sonic frequency brushes. Typically, the frequency range of such brushes is 120-300 Hz, usually producing some slight bristle tip flexing or whipping in addition to oscillation of the bristles. Such separate bristle tip movement usually does not occur in the lower speed scrub-type brushes. An example of such a sonic skin brush appliance and a brushhead is described in U.S. Pat. No. 7,320,691, which is owned by the assignee of the present invention, the contents of which are hereby incorporated by reference.
In some cases, the brushhead and drive system are configured so that portions of the bristle field of the brushhead move in different directions or move out-of-phase with the other portions. Such a particular movement may have advantages in facial cleaning, including the possibility of producing better cleansing with less discomfort. An appliance for producing such action is shown in U.S. Pat. No. 6,032,313. The brushhead assembly includes several concentric brush field portions, which are independently driven by separate mechanical means. However, not only is this a complicated drive structure, but it is not particularly suitable for the sonic speed appliances, because of noise and wear.
It remains desirable that a brushhead arrangement provide out-of-phase and/or counter-rotation action between different groups of bristle tufts but driven by a single drive mechanism.